stack

struct Stack{
    int count;
    int capacity;
    int *elements;
};

struct Stack StackCreate(void){
    struct Stack s = {
        .count = 0,
        .capacity = 0,
        .elements = 0
    };
    return s;
}

void StackExpand(struct Stack *s){
    if(s->capacity == 0) {
        s->capacity++;
    }
    s->capacity *= 2;
    int *temp = realloc(s->elements, sizeof(s->elements[0]) * s->capacity);
    if(temp == NULL){
        fprintf(stderr, "Realloc failed to expand stack.\n");
        exit(1);
    } else {
        s->elements = temp;
    }
}

void StackShrink(struct Stack *s){
    s->capacity = (int)(s->capacity / 1.5f);
    int *temp = realloc(s->elements, sizeof(s->elements[0]) * s->capacity);
    if(temp == NULL){
        fprintf(stderr, "Realloc failed to shrink stack.\n");
        exit(1);
    } else {
        s->elements = temp;
    }
}

void StackPush(struct Stack *s, int input){
    if(s->count == s->capacity){
        StackExpand(s);
    }
    s->elements[s->count++] = input;
}

int StackPop(struct Stack *s){
    if(s->capacity >= s->count * 2.5f) {
        StackShrink(s);
    }
    if(s->count > 1){
        s->count--;
        return (s->elements[s->count]);
    } else {
        fprintf(stderr, "Popped empty stack.\n");
        return 0;
    }
}

void StackPrint(struct Stack *s){
    printf("[");
    for(int i = 0; i < s->count; ++i){
        printf("%X", s->elements[i]);
        if(i < s->count-1){
            printf(",");
        }
    }
    printf("]\n");
    printf("Count:    %i\n", s->count);
    printf("Capacity: %i\n", s->capacity);
}